Virus Breach: How to Recover

PC Mag: A PCMag reader contacted me with a fairly serious problem. He found a gibberish-named item launched at startup from a gibberish folder that, according to Windows Explorer, held zero bytes. If he unchecked the file to keep it from launching at startup, it mysteriously re-checked itself. Clearly he had acquired some sort of polymorphic malware. I asked what sort of security protection was present.